Henry c



UNiTED sTATEs PATENT OFFICE. Y

HENRY C. EGERTON, OF PASSAIC, NEW JERSEY, ASSIGNOR T0 WESTRN ELECTRICCOMPANY, INCORPORATED, OF NEW YORK, N. Y., A CORPORATION 0F' NEW YORK.

PiroNoenAPH-Titnirsnrrrnn.

y* Specification ofLctters Patent.

Patented May 6, 1919i Application mea Maren 13,191'6. seriaiNo. 83,869.

To all whom t may concern.'

Be it known that I, HENRY C.. EGERTON, a citizen of the- United States,residing at Passaic, in the county of Passaic and State of New Jersey,have invented certain new and useful Improvements in Phonograph-Trans'mitters, of which 4the followin is a full,

\ clear concise, and eXact description.

This invention relates to phonograph transmitters, andl moreparticularly to transmitters wherein currents generated inanelectromagnetic system bythe vibrations of a tracing stylus act in atelephone receiver to. produce speech or other sounds present, asrecorded on a phonograph record.

One object of this invention is to provide a highly efficientmagneto-inductive current generating system of this character, in whichthe effective movements of the tracing stylus are of greater amplitude.than the resulting movements of the armature in the magnetoiiiductivesystem. v

Another obj ect. of this inve tion is to pro-v vide an improved phonogrih. transmitter adapted to be assembled in a small symmetricallyformedinclosing case of such convenient shape and size as best adaptedto withstand the handling to which phonograph transmitters arenecessarily subjected, and to better meet and perform the serviceoperations for which they are intended.

A further object of this invention is to provide an improved phonographtransmitter which may be interchangeably positioned to reproduce soundvibrations from either a socalled vertically grooved record or atransversely grooved record.

In accordance with @this invention a magnetoinductive system, comprisinga plurality of pole members, magnetizing coils, and T current'reproducing coils, is provided with an armature of a relativelyconsiderable mass. The armaturerests centrally on one of the polemembers, and is adapted to eXecute a rocking motion of limited amplitudein the magnetic' circuit/zone of ythe several pole members, in responseto vibrations transmitted thereto by means of a motion reducing leveragesystem interposed between the tracing' stylus and the `armature.Cuirrents correspondingly varying in strength and direction aretherebyinduce'd in the cur rent reproducing coils. Therefore a telephonereceiver included `in a circuit with these coils will be operated torepeat the tones represented by the groove on the phonograph record.

In the accompanying drawing, Figure 1 represents, partially inperspective, a side, sectional view of a completely assembledtransmitter. Fig. 2 is a similar view showing the transmitter turnedone-quarter o'r ninety degrees to the l left of the .position shown inFig. 1. Fig. 3 is a diagram of the circuit and vconnections of themagneto-inductive system of this transmitter. Fig. 4 shows, on anenlarged scale, atransversely cut groove of a phonograph record, whichis the'style of record adapted to'be traced when the trans'- initterstylus is in the position shown in Fig. 1, and Fig. 5 shows a'verticallyoutl grooye 4of a phonograph record, which is the style of recordadapted to be traced when the transv`with that shown in Fig. 2.A

Referring tothe drawing, the reference numeral 1 indicates a casingsuitable for mitter stylus is in a position. corresponding inclosing thework-ing parts of the transmitter and also serving as a support forthese enter and close the lower end of the casing 1, is attached to themagnetic frame by means of the brackets 9. The diameter of the disk -6is also less than the inside .diameter of the casing 1; therefore themagnetic system of the transmitter is completely inserted' in the casing1, in whichV position the disk 6 rests against the inside'surface of theend section of the casing, and the diskS enters and seals the mouth ofthe casing chamber. An opening 10, centrally located in the upper endportion ofthe' casing 1, serves as a `port through which the `necessaryexterior conductors enter the transmitter. A slotted opening 11,locatedat a uniform radial distance from theport 10, extends through a.section ofthe end portion of the .casing 1. A screw-threaded boreextending through the disk 6, and into the frame extension 7, is locatedin alinement with the slot 11, land.

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therethrough receives a threaded screw 12. The flange or head of thisscrew is of sufficient diameterto overlap the edges of the shifted toand clamped in either the position shown in Fig. 1, or the positionshown in Fig. 2. It Will be understood that this onequarter rotativeshifting of the transmitter assembly takes place within the casingy 1which remains in the position shown in Fig. 1 with respect to thesupporting arm 2 and U member 4. In Fig. 2 the casing 1 is shown shiftedone-quarter to the-left merely for convenience in showing the manner inwhich the U member 4 is connected thereto.

In describing that portion offthe transmitter assembly which pertainsmore particularly to the moving or vibrating parts thereof, a bridgemember 14 in the form of a spider is rigidly clamped between nuts 15carried by four screw-threaded studs 16 which project from and aresupported by the disk 8. vA pic-ce of suitable resilient or dampingmaterial 17 resting in the bridge member 14, presses a rocking plate 18,having sluitable bearing slots, against the knife-edged ends of twostuds 19 carried by the disk 8. The bearing studs 19 engage .the rockingplate 18 near its ends, and in the side view of this assembly, as shownin Fig. 1, are located behind and in alinement with the screw threadedstuds16 and therefore do not appear in this view. A bore extendingthrough the rocking member 18 continues upwardly into the extension 20of this member, and a bore of. great-er caliber in alinement therewiththrough the bridge A14, and the damping material 17 permits the shank ofa stylus 21 to be inserted therein. The caliber of the bore through 14and 17 gives entire clearance for the shank of the stylus 21, while thebore through 18 and 20 is of a caliber into which lthe stylus 21 isadapted to form a suitable fit. A set screw 22 carried by an enlargedbase portion of the extension 20 and located at substantially the axisof rotation of vthe plate 18 serves to secure the stylus 21 rigidly tothis plate. By locating'thescrew 22 at substantially the axis ofrotation of the plate 18 and extending the stylus across this axis themovement 'of inertia. of this portion of the lever system is materiallyreduced. A bore `23, extending centrally through the disk 8, is of acaliber suiiiciently large to permit clearance for the member 20, whichextends therethrough into the casing 1. A section of spring wire 24serves to form a meclranical connection between the member 20 and anextension member 25 of an armature 26, the wire 24 being' rigidlyconnected to each of the members so joined. The armaon the ole member28. Two curved s Jrino's' 32, rigidly attached to the bridge membert).are adapted to rest on rthe spool heads of magnet poles 27 and 28, andexert pressure to retain the spools in position.

In the magnetic system, the windings 38 and 34 connect to a suitablesource of uni-' directional current (not. shown) and serve to magnetizethe pole members 27 and 29. The resulting magnetic iux completes circuitthrough the armature 26 and the common pole member 28 located midwaybetween and acting magnetically differential with respect to the twopole members 27 and 29. T he windings 35 and 86 respectively associatedwith the poles 27 and 29 represent the current reproducing coils, andwhen connected with a telephone receiver circuit (not shown), generatecurrents therein which correspond in strength and direction with theamplitude, rapidity and direction of movement of the armature 26, all ina well-known manner. Suitable terminals 37, 38, 39 and 40 are providedfor terminating the windings 33, 34, 35 and 36, and for convenience inconnecting the exterior conductors thereto.

In describing the operations which take place in transmitting vibrationsfrom the stylus 21 to the armature 26, let it be assumed that aphonograph record grooved as shown in Fig. 5 is traveling from left toright and in proper Contact with the stylus 21, the transmitter beingheld in the position shown in Fig. 2. The vertically formed indentationsof the record-groove cause the stylus to be vibrated in a directionparallel to the direction in which tthe record is mov-- ing.Accordingly, the plate 18 rocks to and fro on the knife-edged bearingsof the studs 19, and by means of the extension 20, alternate push andpull stresses are applied longitudinally to the spring wire member 24,which in turn sets up reciprocating or rocking movements of the armature26. These movements of the tracing stylus 21 represent the tones whichit is desired to reproduce.l and as the spring member 24 is of suchproportions as not to be appreciably flexed or buckled when pushstresses are applied thereto longitudinally, it will be apparentthat theeffective vibrations are transmitted 'from the stylus 21 to the armature26 over connections in whichelastic losses are prae-v tically avoided.In case the stylus is caused to vibrate in a direction at right anglesto the travel of the record, 'however,'s'uch vibrations, provided theyare not absorbed by the damping material 17, produce'transverse stresseson the spring member 24:, which is suiiiciently flexible to yieldthereto.' Accordingly these transverse vibrations are absorbed and nottransmitted to the armature 26. This feature results in eliminating such.vibrations as do no-t form a part of the ltrue phonograph record,thereby materially improving the distinctness and tone quality of thesoundsreproduced in the telephone receiver.

From the foregoing description in connection with the vertically grovedrecord, it will be apparent that when the transmitter is positioned asshown in Fig. l and a transversely -grooved record similar to that shownin Fig'. i is traced, the effective lateral vibrations of the stylus 21will be transmittedl to the armature 26 and any vertical vibrations willbe absorbed by the spring24. l

In lthe matter of connecting the stylus 21 to the rocking plate 18, itwill be noted that the set screw 22 and the enlarged portion of theextension 20 into which it is threaded, are practically in alinementwith the bearing point present between the rocking plate 18, and theknife-edged bearing studs 19. This feature reduces toa minimum theinertia eect ofthe set screw 2v2, thereby materially increasing theeffectiveness of the transmitter.

A further advantage of the present invention relates to the doublemotion reducing leyerage system, the first of which-is present w1th therocking plate 18 whereby the point of the stylus 21, in tracing arecord,moves a greater distance than the resulting movement at a point on theextension 20 at which the spring 24 is attached; the second motionreducing system being present withl the ar- I mature extension member 25which reduces ,at the point o f the stylus 21. This eature. has anappreclable effect in overcoming thethe amplitude of the movementtransmitted thereto by the spring member 24. Accordingly, the movementof thearmature l26 is considerably less than the initial movementinertia and any momentum tendency of the necessarily heavyv armature,and results'in a considerable gain in the articulation and quality oftone reproduced. A further advantage of this double-levering system,

which acts accumulatively, is to make 1t possible to condense theassembly of the transmitter and inclose it in a. casing 'of relativelymidget proportions, as shown and desorfibed. In order to protect thetransmitter whereby said armatureis moved less than vsaid stylus uponmovement of the latter.

2. In a compact phonograph transmitter, a stylus, a magnet, an inductivecurrent circuit for said magnet, an armature for'said magnet, ,aplurality of compact motion-reducing leverage systems for connectingsaid stylus withisaid armature whereby said ar,-

mature is moved less than said stylus on movement of the latter, and acompact cas; ing adapted to inclose and support the com-l pletelyassembled parts of said 'transmitterll 3. In a phonograph transmitter,means, for generating electric currents, a stylusg means fortransmitting vibrations from said stylus to said current-generatingmeans, a casing adap-ted to inclose and support said transmitter, meansfor assembling said' transmitter independently of said casing, '95 4 andmeans for changing the position of sald transmitter withinsaid casing toadapt said `transmitter to trace either a vertically 'grooved record ora transversely groove'd record. I

.4. In a phonograph transmitter, a stylus, a plurality of magnetpoles,'current inductive circuits for said ma'gret poles, anarmature forsaid magnet poles adapted to be operated by said stylus, and a centraltra-nsverse ridge formedon the face of said armature adapted to seat onone of said magnet poles and permit said armature to execute a rockingmotion thereon'in the iiuX zoneof said magnet poles.

5. Ina phonograph transmitter, amagneto current-generating system, `astylus, a plurality of motion-reducing systems adapt-ed to transmitvibrations from said stylus to said magnetic system whereby vibrations'transmitted to said magnetic system by movement of said stylus are ofsmaller amplitude than corresponding vibrations of said stylus, andresilient dampingmaterial adaptedto retain the working parts of saidtransmitter in their respective operating positions. f

In witness whereof I hereunto subscribe 'my name this 10th day of March,A. D. 1916..

rip-Nar c., EGEnfr-QN. A

